The 19-year-old model steered clear of Kylie Jenner's birthday party on Thursday night.
While her boyfriend, Scott Disick, partied it up with his ex, Kourtney Kardashian, at Jenner's 21st birthday soiree at Delilah in West Hollywood, Richie was spotted across town dining at Nobu with a friend.
The 19-year-old model looked chic in a casual, all-black look as she arrived at the restaurant. Richie couldn't have looked more low-key in oversized pants with white stitching, black satin pointed-toe boots, a matching tank, and slouchy sweatshirt. She appeared to rock minimal makeup, and let her brunette locks hang down over her shoulders.
Richie and Disick fought off reports of a split earlier this summer. A source told ET at the time that the pair -- who vacationed in Greece together last month -- took a little time apart after a fight, but were stronger than ever.
"Scott's friends are happy that he and Sofia worked things out," the source said. "Sofia is really good for Scott; she has a great head on her shoulders and the two get along well. Scott still likes to have a good time, but he's been much calmer while dating Sofia."
Kardashian, meanwhile, split from her former boyfriend, Younes Bendjima, earlier this week. The mother of three got her mind off the breakup at Jenner's party on Wednesday night, where she was surrounded by her sisters -- and Disick. Khloe Kardashian even posted a video of the former couple together, writing, "A girl can dream."
See more on Kourtney's split in the video below.